Jasper County, SC Insulation Payback
Jasper County attic insulation, by the numbers
DOE classifies Jasper County as climate zone 3, hot-humid — summers that stay hot and humid while winters barely register on the energy bill. Its recommended attic R-value for bare joists is R-49. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-49 runs an estimated $2,820, and saves about $869 a year in heating and cooling — a payback around 3.2 years. Topping up the attic pays for itself here.
Heating vs. cooling in Jasper County
Split it out and it's roughly $460 a year on the heating side, $410 on cooling. By estimated insulation savings, Jasper County lands in the 8th percentile nationally. Zone 3 alone covers 690 counties in this dataset, and Jasper County comes in 667th by savings. South Carolina averages $1,016/year across the counties tracked here; Jasper County comes in 14% lower.
The climate data behind this
Jasper County's climate figures — 1,732 heating and 2,570 cooling degree days a year — are read from BEAUFORT MCAS, SC US, 18.1 miles away, NOAA's nearest 1991-2020 normals station. That combined heating-and-cooling load ranks Jasper County 2954th nationally by total degree days — the 7th percentile. One local detail the R-value alone won't tell you: Jasper County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
If the attic isn't bare
A shallower starting point changes the math: with R-11 already down, only the gap to R-38 needs filling, at roughly $1,620 for an estimated $117/year saved (~13.8-year payback). Call this borderline rather than a clear win.
Getting it done in Jasper County
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first. Treat the $2,820 figure above as a planning number for Jasper County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
Jasper County's R-49 target and its degree-day figures both come from named federal sources - see the methodology guide for exactly which ones. The guide to what R-value actually means explains why R-49 is the target here specifically.